Process of producing printing-plates



J. A. H. H'ATT.

PROCESS OF PRODUCING PRINTING PLATES.

APPLICATION FILED APR. 26. I916.

Patented May 6 1919.

vlxlm-v/ll/llllmllv/lllllaa 4 \\\\\\v 4 I I WITNESS. I VENTOR I l I a IJOSEPH ARTHUR HENRY HATT, or BROOKLYN, new YORK.

PROCESS OF PRODUCING PRINTING-PLATES.

Specification of Letters Patent.

Patented May 6, 1919.

Application filed April 26, 1916. Serial No. 93,653.

To all whom it may concern Be it known that I, Josnrrr ARTHUR HENRYHATT, a citizen of the United States, and a resident of Brooklyn, in thecounty of Kings and State of New York, have invented certain new anduseful Improvements in Processes of Producing Printing-Plates, of whichthe followi is a specification.

The invention fel ates to transfer or multiplying processes for, makingprinting plates, and in certain of its aspects more especially to suchprocesses for making planographic printing plates. V

Objects and advantages of the invention will be set-forth in parthereinafter, and in part will be obvious herefrom, the same beingrealized through the steps and processes set out in the appended claims.

The invention consists in the novel steps, process and improvementsherein shown and described.

The accompanying drawings, referred to herein, and constituting a parthereof, illustrate diagrammatically one manner of practising theinvention it being understood that the drawings are diagrammatic andgreatly exaggerated for the sake of clearness, as certain of th thingsshown are very minute and practically microscopic.

Of the drawings:

Figure 1 is a diagram of a design bearing element, such as alithographic stone, or zinc plate;

Fig. 2 shows in edge view, the transfer of the design by meansof offset;

Fig. 3 shows in edge the design trans ferred in a light resistant oropaqu medium to the sensitized surface of a plate;

Fig. 4 shows in edge the exposure of the plate of Fig. 3 to the light;

Fig. 5 shows in central section, corre sponding in positionsubstantially to line A-B of Fig. 1, the developed plate, developedafter beingexposed as shown in Fig. 4;

Fig. 6 shows the printing plate with the design thereon, and

Fig. 7 shows in diagram the optional step of enlarging.

In carrying out my process, any kind of original or copy may beemployed, and the original plate or printing means 1 may be madetherefrom in any of the usual ways. Said original printing means may bea lithographic stone, or a planographic zinc or aluminum plate, ineither case with a suitable design 2 thereon, or it may be a lineongraving or a half-tone plate. Any of these may be used and may beproduced from the Original copy in various well known ways, although alithographic or planographic original printing means is usuallypreferable.

In the prior art it has been customary to multiply such designs upon aprinting plate by taking a plurality of impressions from the originalprinting means, such as the stone or plate above mentioned, on transferpaper, and laying down the various transfer paper impressions in desiredpositions upon the printing plate, which plate is to be used upon thepress in printing simultaneously a plurality of the original designs ateach impression by the press. -As is well known, transfer paper has asoluble surface, consisting ofa very thin layer of glycerin and starch,upon which surface or layer the ink impression of the design is made bythe original printing means, such as the stone or plate. The ink designso impressed on the .soluble surface is placed in contact with, and

becomes adherent upon, the surface of the final printing plate. Thesoluble layer is then moistened, thereby is dissolved, and leaves thedesign upon the printing plate ready to be etched or otherwise preparedfor printing. The use of transfer paper is subj ect to many drawbacks,such as the unavoidable thickening and deterioration of the design,being largely dependent upon the manual skill and good judgment of thetransferrer, and being inevitably subject to a further thickenin anddeterioration in the steps requisite 1n preparing for printing a tainingand increasing the advantages possessed by such printing.

The final printing plate 4, (which in explaining the preferred form ofpractising my invention will be considered as a metal planographicplate, such as the grained planographic and offset presses) is coatedWith a light-sensitive coating 5 upon the grained surface. The solutionfor such a coating may be made from glue or gelatin, with a slightproportion of albumin added thereto, and a light sensitive chromic acidsalt, such as potassium di-chromate. This light-sensitive solution maybe spread over the surface of the plate in any suitable manner, as byflowing the solution over the plate, or by whirling theplate, and thendrying the solution to form the light-sensitive, de sign receivingcoating upon the plate. The design of the original printin' is thenplaced or imprinted upon th means e light sensitive surface of the finalprintingplate as many times as is desired, t e final printing platebeing usually filled with duplications of one or more original designs.The preferred form of so multiplying the designs upon the printing platecomprises inking and, when necessary, otherwise preparing the originalprinting means for making an impression. The impression is then madefrom the original printin means, preferably upon an offset surface, wich may be such a surface as is employed in the rubber offset handpress. In Fig. 3 a hand roller 3 having an ofiset surface is shown,although in commercial practice well known forms of apparatus may beused for this purpose. The design 6 on the offset surface is placed orimprinted in the desired position upon the light sensitive surface ofthe printing plate. By stretching, or varying the tension of, the

offset surface in varyin degrees before and after imprinting the esignthereon from the original printing means, the size of the design on theprinting plate may be made either larger or smaller than the original,as diagrammatically shown in Fig. 7. This operation is repeated untilthe requisite number of inked impressions of the original design of theoriginal printing means has been made upon the light-sensitive surfaceof the final printing plate, that is, usually, until the printing plateis filled. It will be understood, however, that the same original neednot be used throughout, but that various originals may be used, one ormore times.

When the designs are thus impressed on the light-sensitive surface ofthe printing plate, in proper or desired positions, they are preferablyrendered more completelyopaque to light in some suitable manner, as byapplying or rubbing into the ink ofthe design bronze powder, or othersuitable opaquing material. There is thereby secured, in effect, thenegative and the light-sensitive surface 1n one and the same support,and there must, therefore, necessarily be perfect contact and registry.

The light sensitive surface of the plate is then exposed to the actionof light 9 for a lung the surface of the plate with a of absorbentcotton to remove any a hering proper length of time. The light acts onthe light-sensitive layer where not covered by design and renders suchparts insoluble in cold water. Thereafter the ink and powder of thedesigns are washed off from the sensitive surface by a suitable solvent,such as benzin. The plate is then developed, which is done by subjectingthe plate to the action of water, the water dissolving all of thecolloidal surface which was protected by the ink and powder from theaction of the light and therefore remained soluble in water.

- In order to facilitate the development of the plate, and to be able toview the progress of the development to the best advantage, it ispreferable to stain the colloid with an anilin dye, such as a methylviolet. When the plate has been properly developed, it is dried. At thisstage the surface of the late is covered with the indurated or oxi izedcolloid over all the non-design parts, and the portions of the colloid 7which were beneath the design during the exposure to light having beendissolved by the water durin the development, the grained surface 0 theprinting plate is left bare in the design portion.

When the plate is in this condition, the surface there is flowed overwith a very thin solution of light-sensitive asphaltum, which solutionis preferably constituted by dissolving the asphaltum 1n approximatelequal parts of chloroform and benzol. he asphaltum adheres to the designportions of the plate, but in the non-design parts the asmersing theplate in, a Weak a kaline solution, which may be made from potassium hdrate. The development is aided b 3111)- e get particles of the colloid.The non-design portions of the surface of the plate now are bare, whilethe design portion 8 is covered by the layer of light-sensitiveasphaltum and ink.

The plate may then be finished for printing in the usual manner, as byapplying a planographic etch and otherwise proceeding in a known manner.

Where it is desired to reverse the etch, that is to change it from blackto white and vice versa, the surface of the plate is coated with alight-sensitive solution containing only the albumin and omitting theglue, as

the vehicle for the light-sensitive salt. The impressions from theoriginal printing means may be placed upon the light-sensitive surfacein the manner already described and the ink image rendered more opaqueby the application of bronze powder as before. The plate is then exposedto the action of light, and after'such exposure the ink and powder ofthe design are removed from the surface of the plate by means of asuitable solvent, such as benzin. The entire surface of the late is thenevenly coated with a thin film of ink, and is thereafter developed andetched in the usual manner known in the art.

By the present invention a great advantage is effected in that theimpressions from the original printing means are placed upon the smoothlight-sensitive layer, which is better adapted for receiving a clear andsharp impression than is the grained surface of the plate itself whichreceives the impression in the usual transfer process. The im-- pressionupon the sensitive surface, if found defective or undesirable for anyreason, may be easily and quickly washed away by the application of asolvent, such as benzin, without in the least interfering with thelight-sensitive surface itself. A fresh design impression may besubsequently placed at the samespot with perfect results. By myinvention also not only is the thickening and deterioration of thedesign, such as is incident to transfer paper avoided, but the designmay be actually made sharper or lighter upon theprinting plate, or itmay be maintained without thickening simply by controlling or varyingthe duration of the exposure to light. My invention likewise avoids thedifficulty encountered in the use of negatives or like design carrierssuperposed or laid against the light sensitive surface of the plate,namely, the lack of perfect contact with resulting lack of sharpness ofthe design upon the plate, and also avoids the deterioration due to thelight diifusing action of the glass plate or like design carrler.

From all the foregoing it will be understood that a process has beenprovided embodying and realizing the objects and ad vantages herein setforth, together withother objects and advantages; and also, thatdepartures may be made from the precise manner of carrying out theinvention herein described, within the scope of the accompanying claims,without departing from the principles of the invention, and Withoutsacrificing its chief advantages. 7

What ll claim as my invention and desire to secure by Letters Patentis 1. The process of roducing a multi-design printing plate W ichcomprises applying a light sensitive layer to the surface of a finalprinting plate, imprinting on said light sensitized surface impressionsfrom original printing means by means of an insoluble, resilient offsetsurface exposing the designimpressed, light-sensitive surface to the.action of light, and developing and preparing the plate for printing. 2.The process of producing a multi-design printing plate Which comprisesapplying a light sensitive layer to the surface of a final printingplate, changing the size of the design for the printing plate by varyingthe tension of an ofiset surface after it is imprinted by an originalprinting means and before imprinting on the sensitized surface,imprinting, on said light sensitized surface impressions from originalprinting means by means of the ofiset surface, exposing thedesign-impressed light-sensitive surface to the action of light, anddeveloping and preparing the plate for printing. 3. The process ofroducing a multi-design printing plate w iich comprises placing upon thegrained surface of a planograph1c printing plate a smooth layer of lightsensitive material, imprinting a design by means of an insoluble,resilient offset surface upon the surface of said light sensitive layerin a light arresting medium, exposing the design imprinted, lightsensitive surface to the action of light, removing the designconstituting material from the light sensitive surface, dissolving theportions of the light sensitlve material which were beneath the designduring the exposure of the light sensitive surface to the light, placinga design constituting material upon the exposed design portion of thegrained surface of the printing plate, and removing the portions of thelight sensitive layer remaining on the non-design portions of thesurface of the printing plate.

t. The process of producing a multi-de- 1 sign printing plate whichcomprises placing 'upon the grained surface of a planographic printingplate a smooth layer of light sensitive' material, imprinting a designby means I of an insoluble, resilient ofi'set surface upon the surfaceof said light sensitive layer in a light arresting medium, exposing thedesign imprinted, light sensitive surface to the action of light,dissolving the portions of the 7 upon the grained surface of aplanographic printing plate a smooth layer of light sensi t1ve material,imprinting a design by means of an insoluble, resilient ofiset surfaceupon the surface of said light sensitive layer in a light arrestingmedium, exposing the designimprinted, light-sensitive surface to theaction of light, dissolving the design and the parts of the sensitivelayer therebeneatlr which were not acted upon by the light, applying adesign material to the so exposed portions of the ained surface of theprinting plate, and dissolving the portions of the light sensitive layerremaining on the nondpsign portion of the surface of the printing p ate.

6. The process of producing a multi-design printing plate whichcomprises placing upon the grained surface of a planographic printingplate a smooth layer of light sensitive material, imprinting a design bymeans of an insoluble, resilient offset surface upon the surface of saidlight sensitive layer in a light arresting medium, exposing thedesignimprinted, light-sensitivesurface to the action of light, applyingto the surface of the plate a medium which Will dissolve the design butwhich will not dissolve the sensitive layer, applying to the sensitivelayer a medium which will dissolve only the portions of such layer whichhave not been acted upon by light, applying a design constitutingmaterial to the portlons of the grained surface of the plate therebyexposed, and applying a solvent to the'light sensitive layer remaininupon the non-design portions of the plate.

The, process of producing a multi-design printing plate which comprisesapplying a smooth light sensitive layer to the grained surface of aprinting plate, imprinting a plurality of designs by means of aninsoluble,resilient ofl'set surface in desired positions upon saidsmooth light sensitive layer from original printing means by means of anoffset surface, exposing the sensitized and design imprinted surface tothe action of light, dissolving the imprinted designs from the exposedsurface, dissolving the portions of the light sensitive layer which wereprotected from the light action by the design, applying a designmaterial to the portions of the printing plate so exposed, anddissolving the remainder of the light sensitive layer from thenon-design portion of the plate.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing Witnesses.

JOSEPH ARTHUR HENRY HATT.

Witnesses:

JOHN D. MORGAN, LOUISA LOEHR.

